TM 5-3610-285-14
(e)
When the developer reaches temperature, the collector of transistor Q1 on circuit board 700 goes
high and pin 3 of U1 on circuit board 1000 goes high. A high is then provided to pin 1 of U2. Since the output of U3
goes high for a short duration (approximately 10 to 12 seconds), pin 2 of U2 also goes high. U2A and U2B provide a low
at pin 3 of U2. Pin 10 of U2B goes low, turns off transistor Q1, and causes a high at pin 14 of U1 on circuit board 500.
The low at pin 10 of U2B also turns on transistor Q2, energizes relay K1001, and turns on solenoid valve L3. Solenoid
valve L3 provides water to the heat exchanger to help control the developer temperature.
(f)
If warm wash water is flowing and THS2 is normally open, then L1 is turned off and L2 is turned on to
provide additional water flow through the heat exchanger.
(g)
The high at pin 14 of U1 on circuit board 500 results in a high at pin 1 of U6. No film at the detector
switches (MS1 and MS2) results in a high at pin 2 of U6 and with both inputs of U6 high, pin 10 of U5 goes low. This
triggers the film clear timer U2'and causes the output formed by pins 1 through 8 to go low.
(h)
When the film clear timer U2 times out and enters the standby mode, the output goes high and
provides clock pulse to U9.
(i)
When U9 receives this pulse, pin 2 goes high and turns off transistor Q3, which turns off relay K602.
(j)
If cold wash water is flowing and THS2 is normally closed, solenoid valve LI turns off.
i.
Standby Control Circuit.
(1)
The processor will automatically switch to the standby mode, to reduce water and electricity usage,
approximately 6 minutes after last piece of film clears the detector switches. The standby control circuit can be bypassed
by operating the toggle switch on circuit board 500.
(2)
Circuit description. The standby control circuit is dependent upon the water control circuit, which is
dependent upon the developer temperature control circuit for proper operation. However, developer temperature control
is maintained independently of the standby mode as follows:
(a)
Circuit board 700.
1
The voltage divider network resistors R2, R3, and R4, on circuit board 700 provide the reference
voltage to pin 3 of voltage comparator U1 on circuit board 700. The desired developer temperature is selected by
adjusting resistor R4 which establishes the desired reference voltage at pin 3 of U1.
2
If the voltage at pin 2 is greater than the voltage at pin 3, the output at pin 7 goes high. Transistor
Q1 on circuit board 700 is turned on when the collector goes low, thereby turning on the CR1 LED.
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